Wow, that's an interesting quirk indeed. Maybe DirectX is muted somehow? You could try running Kana, and then ending the process through task manager. Does this problem also occur if you run the standard Kana exe?

Closing the game through task manager also ends the sound.
When I run the game with the original exe no sound plays, it seems directly related to the patch.
One thing I forogt to mention:
I never had the problem with patch before, this time I switched to fullscreen with the patch for the first time...
Maybe it's related to the library functions of it, which somehow cause the error.
Oh, and thanks for the fast reply! ^^